Happy Days are here again! Alums Scott Baio and Garry Marshall are reuniting on Baio's Nick at Nite show See Dad Run, according to The Hollywood Reporter.

Marshall guest-stars on this week's episode as Bernie, the TV dad of Baio's character David, a former sitcom star who's now a stay-at-home dad. David becomes annoyed when Bernie runs off and leaves his new (real-life) baby, THR reports.

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"I thought the whole week I would be so nervous in front of him. I wanted to be great in front of him, and I didn't want to blow it," Baio tells THR. "But as soon as we started, it was the most relaxed I've ever been, and it was just so easy. And it was incredibly emotional, and I'm not really an emotional guy."

Baio said he brought up Marshall's name when producers were looking to cast his character's father, and also asked Marshall's son Scott to direct the episode. "I have a policy: I answer calls from people who made me a hit," Marshall told THR.

In another coincidence, See Dad Run also films on the same stage as Happy Days did. The episode airs Sunday at 8/7c on Nickelodeon.